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Estrogen receptor positive tumors: do reproductive factors explain differences in incidence between black and white women?

Abstract

PURPOSE

The incidence of estrogen receptor positive (ER+) breast cancer is higher among white women relative to black women. In two large prospective cohorts, the Black Women's Health Study (BWHS) and the Nurses' Health Study II (NHSII), we investigated whether reproductive factors explain the difference.

METHODS

During 1,582,083 person-years of follow-up of 140,914 women observed from 1995 to 2007, 327 ER+ breast cancers were identified among black women in BWHS and NHSII and 1,179 among white women in NHSII. Cox proportional hazards regression models, stratified by race and pooled, were used to estimate hazard ratios (HR) and 95 % confidence intervals (CI) for the association of race, parity, age at first birth, and lactation in relation to risk of ER+ cancer with adjustment for age and other breast cancer risk factors.

RESULTS

Age at first birth differed markedly in the two groups, with 66 % of parous black women having their first child before age 25 as compared with 36 % of white women. Each additional year of age at first birth was associated with a 4 % increased risk of ER+ breast cancer among both racial groups. Relative to nulliparous women, parous women were at decreased risk of ER+ breast cancer (HR 0.59, 95 % CI 0.20, 1.77), in black women and (HR 0.63, 95 % CI 0.45, 0.87) in white women. The HR for the association of black race with ER+ cancer was 0.67 (95 % CI 0.53, 0.84) in a model that adjusted for age only, 0.77 (95 % CI 0.61, 0.99) in a model that controlled for parity, age at first birth, and other reproductive/hormonal factors, and 0.83 (95 % CI 0.70, 0.98) in a model that additionally controlled for other breast cancer risk factors such as alcohol consumption and use of hormone supplements. Similar associations were seen among premenopausal women and in an analysis restricted to ER+PR+ tumors.

CONCLUSIONS

Reproductive factors explained some of the higher incidence of ER+ tumors among white women as compared to black women.

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  • Authors+Show Affiliations

    ,

    Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA. ewarner@hsph.harvard.edu

    , , , , ,

    Source

    Cancer causes & control : CCC 24:4 2013 Apr pg 731-9

    MeSH

    Adult
    African Americans
    Aged
    Boston
    Breast Neoplasms
    European Continental Ancestry Group
    Female
    Follow-Up Studies
    Humans
    Incidence
    Middle Aged
    Nurses
    Prognosis
    Prospective Studies
    Receptors, Estrogen
    Receptors, Progesterone
    Reproduction
    Risk Factors
    Women's Health
    Young Adult

    Pub Type(s)

    Comparative Study
    Journal Article
    Research Support, N.I.H., Extramural
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    23380944

    Citation

    Warner, Erica T., et al. "Estrogen Receptor Positive Tumors: Do Reproductive Factors Explain Differences in Incidence Between Black and White Women?" Cancer Causes & Control : CCC, vol. 24, no. 4, 2013, pp. 731-9.
    Warner ET, Tamimi RM, Boggs DA, et al. Estrogen receptor positive tumors: do reproductive factors explain differences in incidence between black and white women? Cancer Causes Control. 2013;24(4):731-9.
    Warner, E. T., Tamimi, R. M., Boggs, D. A., Rosner, B., Rosenberg, L., Colditz, G. A., & Palmer, J. R. (2013). Estrogen receptor positive tumors: do reproductive factors explain differences in incidence between black and white women? Cancer Causes & Control : CCC, 24(4), pp. 731-9. doi:10.1007/s10552-013-0153-9.
    Warner ET, et al. Estrogen Receptor Positive Tumors: Do Reproductive Factors Explain Differences in Incidence Between Black and White Women. Cancer Causes Control. 2013;24(4):731-9. PubMed PMID: 23380944.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Estrogen receptor positive tumors: do reproductive factors explain differences in incidence between black and white women? AU - Warner,Erica T, AU - Tamimi,Rulla M, AU - Boggs,Deborah A, AU - Rosner,Bernard, AU - Rosenberg,Lynn, AU - Colditz,Graham A, AU - Palmer,Julie R, Y1 - 2013/02/05/ PY - 2012/05/15/received PY - 2013/01/15/accepted PY - 2013/2/6/entrez PY - 2013/2/6/pubmed PY - 2013/9/13/medline SP - 731 EP - 9 JF - Cancer causes & control : CCC JO - Cancer Causes Control VL - 24 IS - 4 N2 - PURPOSE: The incidence of estrogen receptor positive (ER+) breast cancer is higher among white women relative to black women. In two large prospective cohorts, the Black Women's Health Study (BWHS) and the Nurses' Health Study II (NHSII), we investigated whether reproductive factors explain the difference. METHODS: During 1,582,083 person-years of follow-up of 140,914 women observed from 1995 to 2007, 327 ER+ breast cancers were identified among black women in BWHS and NHSII and 1,179 among white women in NHSII. Cox proportional hazards regression models, stratified by race and pooled, were used to estimate hazard ratios (HR) and 95 % confidence intervals (CI) for the association of race, parity, age at first birth, and lactation in relation to risk of ER+ cancer with adjustment for age and other breast cancer risk factors. RESULTS: Age at first birth differed markedly in the two groups, with 66 % of parous black women having their first child before age 25 as compared with 36 % of white women. Each additional year of age at first birth was associated with a 4 % increased risk of ER+ breast cancer among both racial groups. Relative to nulliparous women, parous women were at decreased risk of ER+ breast cancer (HR 0.59, 95 % CI 0.20, 1.77), in black women and (HR 0.63, 95 % CI 0.45, 0.87) in white women. The HR for the association of black race with ER+ cancer was 0.67 (95 % CI 0.53, 0.84) in a model that adjusted for age only, 0.77 (95 % CI 0.61, 0.99) in a model that controlled for parity, age at first birth, and other reproductive/hormonal factors, and 0.83 (95 % CI 0.70, 0.98) in a model that additionally controlled for other breast cancer risk factors such as alcohol consumption and use of hormone supplements. Similar associations were seen among premenopausal women and in an analysis restricted to ER+PR+ tumors. CONCLUSIONS: Reproductive factors explained some of the higher incidence of ER+ tumors among white women as compared to black women. SN - 1573-7225 UR - https://www.unboundmedicine.com/medline/citation/23380944/Estrogen_receptor_positive_tumors:_do_reproductive_factors_explain_differences_in_incidence_between_black_and_white_women L2 - https://doi.org/10.1007/s10552-013-0153-9 DB - PRIME DP - Unbound Medicine ER -